691 research outputs found

    SAMICS: Input data preparation

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    The Solar Array Manufacturing Industry Costing Standards (SAMICS) provide standard formats, data, assumptions, and procedures for estimating the price that a manufacturer would have to charge for the product of a specified manufacturing process sequence. A line-by-line explanation is given of those standard formats which describe the economically important characteristics of the manufacturing processes and the technological structure of the companies and the industry. This revision provides an updated presentation of Format A Process Description, consistent with the October 1978 version of that form. A checklist of items which should be entered on Format A as direct expenses is included

    Formation and Structure of Circumplanetary Disks and Envelopes during the Late Stages of Giant Planet Formation

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    Giant planets are expected to form within circumstellar disks, which shape their formation history and the local environment. Here, we consider the formation and structure of circumplanetary disks that arise during the late stages of giant planet formation. During this phase, when most of the final mass is accumulated, incoming material enters the Hill sphere and falls toward the planet. In the absence of torques, the falling parcels of gas conserve their specific angular momentum and collect into a circumplanetary disk. Generalizing previous work, we consider a range of possible geometries for the flow entering the sphere of influence of the planet. Specifically, we consider five geometric patterns for the inward flow, ranging from concentration toward the rotational poles of the system to isotropic flow to concentration along the equatorial plane. For each case, we derive analytic descriptions for the density field of the infall region, the disk surface density in the absence of viscosity, and steady-state solutions for viscous disks. These results, in turn, specify the luminosity contributions of the planet, the circumplanetary disk, and the envelope. These power sources, in conjunction with the surrounding material, collectively determine the observational appearance of the forming planet. We conclude with an approximate determination of these radiative signatures.Comment: 19 pages, 9 figures. Published at Icaru

    Management issues in systems engineering

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    When applied to a system, the doctrine of successive refinement is a divide-and-conquer strategy. Complex systems are sucessively divided into pieces that are less complex, until they are simple enough to be conquered. This decomposition results in several structures for describing the product system and the producing system. These structures play important roles in systems engineering and project management. Many of the remaining sections in this chapter are devoted to describing some of these key structures. Structures that describe the product system include, but are not limited to, the requirements tree, system architecture and certain symbolic information such as system drawings, schematics, and data bases. The structures that describe the producing system include the project's work breakdown, schedules, cost accounts and organization

    Extended Kramers-Moyal analysis applied to optical trapping

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    The Kramers-Moyal analysis is a well established approach to analyze stochastic time series from complex systems. If the sampling interval of a measured time series is too low, systematic errors occur in the analysis results. These errors are labeled as finite time effects in the literature. In the present article, we present some new insights about these effects and discuss the limitations of a previously published method to estimate Kramers-Moyal coefficients at the presence of finite time effects. To increase the reliability of this method and to avoid misinterpretations, we extend it by the computation of error estimates for estimated parameters using a Monte Carlo error propagation technique. Finally, the extended method is applied to a data set of an optical trapping experiment yielding estimations of the forces acting on a Brownian particle trapped by optical tweezers. We find an increased Markov-Einstein time scale of the order of the relaxation time of the process which can be traced back to memory effects caused by the interaction of the particle and the fluid. Above the Markov-Einstein time scale, the process can be very well described by the classical overdamped Markov model for Brownian motion.Comment: 14 pages, 18 figure

    The multifunctional autophagy pathway in the human malaria parasite, Plasmodium falciparum.

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    Autophagy is a catabolic pathway typically induced by nutrient starvation to recycle amino acids, but can also function in removing damaged organelles. In addition, this pathway plays a key role in eukaryotic development. To date, not much is known about the role of autophagy in apicomplexan parasites and more specifically in the human malaria parasite Plasmodium falciparum. Comparative genomic analysis has uncovered some, but not all, orthologs of autophagy-related (ATG) genes in the malaria parasite genome. Here, using a genome-wide in silico analysis, we confirmed that ATG genes whose products are required for vesicle expansion and completion are present, while genes involved in induction of autophagy and cargo packaging are mostly absent. We subsequently focused on the molecular and cellular function of P. falciparum ATG8 (PfATG8), an autophagosome membrane marker and key component of the autophagy pathway, throughout the parasite asexual and sexual erythrocytic stages. In this context, we showed that PfATG8 has a distinct and atypical role in parasite development. PfATG8 localized in the apicoplast and in vesicles throughout the cytosol during parasite development. Immunofluorescence assays of PfATG8 in apicoplast-minus parasites suggest that PfATG8 is involved in apicoplast biogenesis. Furthermore, treatment of parasite cultures with bafilomycin A 1 and chloroquine, both lysosomotropic agents that inhibit autophagosome and lysosome fusion, resulted in dramatic morphological changes of the apicoplast, and parasite death. Furthermore, deep proteomic analysis of components associated with PfATG8 indicated that it may possibly be involved in ribophagy and piecemeal microautophagy of the nucleus. Collectively, our data revealed the importance and specificity of the autophagy pathway in the malaria parasite and offer potential novel therapeutic strategies

    Seasonal and spatial variations in the ocean-coupled ambient wavefield of the Ross Ice Shelf

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    © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Baker, M. G., Aster, R. C., Anthony, R. E., Chaput, J., Wiens, D. A., Nyblade, A., Bromirski, P. D., Gerstoft, P., & Stephen, R. A. Seasonal and spatial variations in the ocean-coupled ambient wavefield of the Ross Ice Shelf. Journal of Glaciology, 65(254), (2019): 912-925, doi:10.1017/jog.2019.64.The Ross Ice Shelf (RIS) is host to a broadband, multimode seismic wavefield that is excited in response to atmospheric, oceanic and solid Earth source processes. A 34-station broadband seismographic network installed on the RIS from late 2014 through early 2017 produced continuous vibrational observations of Earth's largest ice shelf at both floating and grounded locations. We characterize temporal and spatial variations in broadband ambient wavefield power, with a focus on period bands associated with primary (10–20 s) and secondary (5–10 s) microseism signals, and an oceanic source process near the ice front (0.4–4.0 s). Horizontal component signals on floating stations overwhelmingly reflect oceanic excitations year-round due to near-complete isolation from solid Earth shear waves. The spectrum at all periods is shown to be strongly modulated by the concentration of sea ice near the ice shelf front. Contiguous and extensive sea ice damps ocean wave coupling sufficiently so that wintertime background levels can approach or surpass those of land-sited stations in Antarctica.This research was supported by NSF grants PLR-1142518, 1141916, 1142126, 1246151 and 1246416. JC was additionally supported by Yates funds in the Colorado State University Department of Mathematics. PDB also received support from the California Department of Parks and Recreation, Division of Boating and Waterways under contract 11-106-107. We thank Reinhard Flick and Patrick Shore for their support during field work, Tom Bolmer in locating stations and preparing maps, and the US Antarctic Program for logistical support. The seismic instruments were provided by the Incorporated Research Institutions for Seismology (IRIS) through the PASSCAL Instrument Center at New Mexico Tech. Data collected are available through the IRIS Data Management Center under RIS and DRIS network code XH. The PSD-PDFs presented in this study were processed with the IRIS Noise Tool Kit (Bahavar and others, 2013). The facilities of the IRIS Consortium are supported by the National Science Foundation under Cooperative Agreement EAR-1261681 and the DOE National Nuclear Security Administration. The authors appreciate the support of the University of Wisconsin-Madison Automatic Weather Station Program for the data set, data display and information; funded under NSF grant number ANT-1543305. The Ross Ice Shelf profiles were generated using the Antarctic Mapping Tools (Greene and others, 2017). Regional maps were generated with the Generic Mapping Tools (Wessel and Smith, 1998). Topography and bathymetry data for all maps in this study were sourced from the National Geophysical Data Center ETOPO1 Global Relief Model (doi:10.7289/V5C8276M). We thank two anonymous reviewers for suggestions on the scope and organization of this paper

    Fitting the Light Curve of 1I/`Oumuamua with a Nonprincipal Axis Rotational Model and Outgassing Torques

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    In this paper, we investigate the nonprincipal axis (NPA) rotational state of 1I/`Oumuamua -- the first interstellar object discovered traversing the inner Solar System -- from its photometric light curve. Building upon Mashchenko (2019), we develop a model which incorporates NPA rotation and {Sun-induced, time-varying} outgassing torques to generate synthetic light curves of the object. The model neglects tidal forces, which are negligible compared to outgassing torques over the distances that `Oumuamua was observed. We implement an optimization scheme that incorporates the NPA rotation model to calculate the initial rotation state of the object. We find that an NPA rotation state with an average period of ⟨P⟩≃7.34\langle P \rangle\simeq7.34 hr best reproduces the photometric data. The discrepancy between this period and previous estimates is due to continuous period modulation induced by outgassing torques in the rotational model, {as well as different periods being used}. The best fit to the October 2017 data does not reproduce the November 2017 data (although the later measurements are too sparse to fit). The light curve is consistent with no secular evolution of the angular momentum, somewhat in tension with the empirical correlations between nuclear spin-up and cometary outgassing. The complex rotation of `Oumuamua may be {the result of primordial rotation about the smallest principal axis} if (i) the object experienced hypervolatile outgassing and (ii) our idealized outgassing model is accurate.Comment: 22 pages, 8 figures, 1 animation. Accepted to the Planetary Science Journal. The animation can be found on YouTube (https://youtu.be/f5YEAMTvIeo) and in the online publication by PSJ (when available
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